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James DeGregori, Professor

Ph.D. (1993), Massachusettes Institute of Technology


 

 

 

Contact Info:

Molecular Biology
University of Colorado

James DeGregori, Ph.D.  Research One South
(RC1-South), Room 9103
James.DeGregori@ucdenver.edu Phone: 303-724-3230

My lab primarily works with mouse models, and we frequently use gene knock-out mice and retroviral models of leukemogenesis. Studies to better understand the conditions that foster the initiation of leukemias and lymphomas are currently a major thrust of the lab. In particular, we are investigating how conditions of stress (such as those that impair DNA replication) promote the competitive expansion of cells expressing particular oncogenes, and the mechanism whereby these oncogenes can improve cell cycle progression and survival under conditions of stress. We are exploring how reduced progenitor cellular fitness resulting from carcinogen exposure, inadequate diet or aging can select for adaptive oncogenic events and thereby promote the expansion and fixation of oncogenically initiated cells. While current views of carcinogenesis focus on oncogenic mutations as the limiting step, our studies support a novel rationale for links between tumorigenesis and carcinogenic contexts: these contexts may promote the clonal expansion of cells bearing particular initiating events, in part by reducing progenitor pool fitness which selects for adaptive oncogenic mutations.

Other studies in the lab are geared towards the development of novel therapeutic strategies to treat leukemias. We perform genome-wide loss-of-function screens using RNA interference (RNAi) to identify genes whose inhibition will synergize with current targeted therapeutics to eliminate leukemic cells. Our screens have identified a number of genes that synergistically inhibit chronic myelogenous leukemia cells in combination with the drug imatinib mesylate, and these genes have been validated as therapeutic targets by using both pharmacological and genetic approaches. These studies could lead to discovery of adjuvants to current therapies that will more effectively treat or possibly even cure common blood malignancies. Finally, other studies in the lab are testing whether yeast-based immunotherapies targeting drug resistance mutations can effectively prevent the development of drug resistant leukemias. ​​​​​​​​​

 

Marusyk, A. and J. DeGregori (2007). Declining cellular fitness with age promotes cancer initiation by selecting for adaptive oncogenic mutations (theory paper). BBA Reviews on Cancer 1785: 1-11.

Porter, C.P. and J. DeGregori (2008). Interfering RNA-mediated purine analog resistance for in vitro and in vivo cell selection. Blood 112, 4466-4474.

Marusyk A., M. Casás-Selves, C. J. Henry, V. Zaberezhnyy, J. Klawitter, U. Christians and J. DeGregori (2009). Irradiation alters selection for oncogenic mutations in hematopoietic progenitors. Cancer Research 69, 7262-7269.

Marusyk A, C. Porter, V. Zaberezhnyy and J. DeGregori (2010). Irradiation selects for p53 deficient hematopoietic progenitors. PLoS Biology, 8:e1000324.

Gregory, M., T. Phang, P. Neviani, F. Alvarez-Calderon, V. Zaberezhnyy, R. Williams, T. O’Hare, C. Eide, B. Druker, D. Perrotti and J. DeGregori (2010). Wnt/Ca2+/NFAT signaling maintains survival of Ph+ leukemia cells upon inhibition of Bcr-Abl. Cancer Cell, 18, 74-87.

Henry, C.J., A. Marusyk, B. Adane, V. Zaberezhnyy and J. DeGregori (2010). Declining lymphoid progenitor fitness promotes aging-associated leukemogenesis. Proc. Natl. Acad. Sci. USA, 107: 21713-21718.